Monitoring underground coal mining - induced subsidence

Monitoring of mine subsidence by means of classical methods such as optical levelling or Global Positioning System (GPS) surveys can reveal deformations with sub-millimetre to subcentimetre precision for localised areas. However, to provide data on a reasonably dense two-dimensional (2D) benchmark grid are costly and time-consuming for all but the smallest areas. Moreover, a regular re-survey of a mining region may be required, and a retrospective study of a specific deformation event is usually not possible since monitoring networks are often implemented after the major events have occurred.